Hensman Moss 1

C9orf72 expansions are the most common genetic cause of Huntington’s disease

phenocopies

Authors and Affiliations:

Davina J. Hensman Moss BA MBBS2, Mark Poulter BSc1, Jon Beck BSc1, Jason Hehir BSc3, James

M. Polke PhD3, Tracy Campbell BSc1, Garry Adamson BSc1, Ese Mudanohwo BSc3, Peter

McColgan MSc MBChB2, Andrea Haworth MSc3, Edward J. Wild MBChB PhD2, Mary G. Sweeney

BSc3, Henry Houlden MBChB PhD3, 4, Simon Mead MBChB PhD*2, Sarah J. Tabrizi MBChB PhD*2

*denotes equal senior author

1 MRC Prion Unit, 2Department of Neurodegenerative Disease , UCL Institute of Neurology Queen

Square, London WC1N 3BG

3 Neurogenetics Unit, National Hospital for Neurology and Neurosurgery, University College London

Hospitals, Queen Square, London WC1N 3BG

4 Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London

WC1N 3BG

Corresponding author

Professor Sarah Tabrizi, Box 104, UCL Institute of Neurology, University College London, Queen

Square, London WC1N 3BG, UK. s.tabrizi@prion.ucl.ac.uk Tel: 020 3448 4434 Fax: 020 7611

0129.

Supplementary data: supplemental patient clinical information regarding case histories.

Email addresses of authors: d.hensman@ucl.ac.uk; m.poulter@prion.ucl.ac.uk; j.beck@prion.ucl.ac.uk; jason.hehir@uclh.nhs.uk; james.polke@uclh.nhs.uk; t.campbell@prion.ucl.ac.uk; g.adamson@prion.ucl.ac.uk; ese.mudanohwo@uclh.nhs.uk; p.mccolgan@ucl.ac.uk; andrea.haworth@icr.ac.uk, e.wild@ucl.ac.uk; mary.sweeney@uclh.nhs.uk; h.houlden@ucl.ac.uk; s.mead@prion.ucl.ac.uk; s.tabrizi@prion.ucl.ac.uk

Number of characters in title: 88 (max 96) Word count for paper: 2884 (max 3000); [Introduction 249 words (max 250)] Word count for abstract: 223 (max 250) Number of tables: 3 (max 5 tables & figures) Number of figures: 2 (max 5 tables & figures) Number of references: 36 (max 40)

Hensman Moss 2

Statistical analysis

Dr Hensman Moss completed the statistical analysis and was supervised in this by Dr Mead.

Search terms

14 – All Clinical Neurology; 91 – All Genetics; 161 – All Movement Disorders; 164 – Huntington’s

disease; 199 – All Neuropsychology/Behaviour.

Author Contributions

Davina Hensman Moss: Drafting/revising the manuscript for content, Study design, Analysis & interpretation of data, Acquisition of data, Statistical Analysis. Mark Poulter: Execution, Drafting/revising the manuscript, Acquisition of data, Analysis & interpretation of data. Jon Beck: Revising the manuscript, Study design, Analysis & interpretation of data James M Polke: Revising the manuscript, Analysis & interpretation of data

Tracy Campbell: Revising the manuscript, Acquisition of data, Analysis or interpretation of data

Garry Adamson: Revising the manuscript, Acquisition of data, Analysis or interpretation of data

Jason Hehir: Revising the manuscript, Acquisition of data, Analysis or interpretation of data

Ese Mudanohwo: Revising the manuscript, Analysis or interpretation of data

Peter McColgan: Revising the manuscript, Acquisition of data

Andrea Haworth: Study concept or design, Revising the manuscript

Edward J Wild: Revising the manuscript, Analysis or interpretation of data

Mary G Sweeney: Study concept or design, Revising the manuscript

Henry Houlden: Study concept or design, Analysis or interpretation of data

Simon Mead: Study concept or design, Revising the manuscript, Analysis & interpretation of data,

Study supervision

Sarah J Tabrizi: Study concept or design, Revising the manuscript, Analysis & interpretation of data,

Study supervision

Study Funding

This work was undertaken at University College London Hospitals (UCLH)/University College

London (UCL), which received a proportion of funding from the Department of Health’s National

Institute for Health Research Biomedical Research Centres funding scheme. SM, JB, MP, GA are

funded by the Medical Research Council- MRC Prion Unit. TC is funded by UCL. EJW is supported

by the National Institutes for Health Research. The work in SJT’s lab is supported financially by

BBSRC, UCL/UCLH Biomedical Research Centre, Medical Research Council, CHDI Foundation,

EU FP7 grant (Paddington and Neuromics consortia), and the UK Dementia and Neurodegenerative

Diseases Network (DeNDRoN).

Disclosures: The authors report no disclosures relevant to the manuscript

Hensman Moss 3

Abstract

Objective: In many cases where Huntington’s disease (HD) is suspected, the genetic test

for HD is negative: these are known as HD phenocopies. A repeat expansion in the

C9orf72 gene has recently been identified as a major cause of familial and sporadic

frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Our

objective was to determine whether this mutation causes HD phenocopies.

Methods: A cohort of 514 HD phenocopy patients were analysed for the C9orf72

expansion using repeat-primed PCR. In cases where the expansion was found, Southern

hybridisation was performed to determine expansion size. Clinical case notes were

reviewed to determine the phenotype of expansion-positive cases.

Results: 10 subjects (1.95%) had the expansion, making it the commonest identified

genetic cause of HD-phenocopy presentations. The size of expansion was not significantly

different from that associated with other clinical presentations of C9orf72 expanded cases.

The C9orf72 expansion-positive subjects were characterised by the presence of movement

disorders including dystonia, chorea, myoclonus, tremor and rigidity. Furthermore the age

of onset in this cohort was lower than previously reported for subjects with the C9orf72

expansion, and included one case with paediatric onset.

Discussion: This study extends the known phenotype of the C9orf72 expansion, both in

age of onset and movement disorder symptoms. We propose a revised clinico-genetic

algorithm for the investigation of HD-phenocopy patients based on these data.

Hensman Moss 4

Introduction

Huntington’s disease (HD) is an autosomal dominantly inherited neurodegenerative

condition typically characterised by a triad of psychiatric, movement and cognitive

impairment. In many cases where HD is suspected clinically, patients lack the CAG repeat

expansion that causes HD1-4. Such individuals are said to have HD phenocopy syndromes

or HD-like disorders5. Wild & Tabrizi3 reviewed genes identified in different HD phenocopy

cohorts to determine that Spinocerebellar ataxia 17 (TBP) accounts for 1.1%, Huntington’s

Disease-Like 2 (HDL2) for 0.7%, Friedreich’s ataxia (JPH3) for 0.35% and inherited prion

disease (PRNP) for 0.24% of HD phenocopies. Testing for these mutations is now routinely

performed; however the majority of HD phenocopy patients still do not attain a formal

genetic diagnosis.

In 2011 an expanded hexanucleotide repeat in the C9orf72 gene was identified in large

kindreds with FTLD and ALS6, 7. This expansion is recognised as the commonest genetic

cause of ALS and FTLD in many but not all populations6-9. The mutation is intronic, in a

highly conserved gene6, 10 which has homology with the DENN-like superfamily suggesting

a role as regulator of membrane traffic10-12, and which may be involved in other neurological

conditions13. Several hundred-thousands of repeats have been documented in pathogenic

expansions14. Elucidating the pathogenic mechanism of this expansion has generated

much interest; several non-mutually exclusive possibilities exist6, 15-19.

In this study we undertook to examine whether the C9orf72 expansion causes HD

phenocopy clinical presentations, and hence whether testing for it should be considered in

the routine genetic work-up of this patient group.

Hensman Moss 5

Subjects and methods

Case ascertainment

As previously described20, subjects were classified as having HD phenocopy syndromes on

the basis of a clinical presentation consistent with HD when assessed by an experienced

neurologist or neurogeneticist, and a negative test for the expanded CAG repeat in the HTT

gene which causes HD (<36 repeats). At the Neurogenetics Unit of the National Hospital

for Neurology and Neurosurgery (NHNN), London, UK, 63.5% of diagnostic HD tests (those

done on symptomatic patients) are negative for HD. A cohort of 514 HD phenocopy cases

who underwent negative diagnostic genetic testing for HD at NHNN were identified. The

average age at onset in this cohort was 48.8 years in those with precise onset data (SD

19.3, N=176). 300 subjects were seen at NHNN, 214 at other hospitals. Of those seen at

NHNN, 45.3% were seen by a Movement Disorders Consultant, 15.3% by a Cognitive

Disorders Consultant, 14.3% by a Neurogenetics Consultant and 25% by other Consultant

Neurologists.

Clinical summaries were reviewed for all cases, and all available clinical case notes

reviewed for cases positive for the C9orf72 expansion mutation. Demographic data, family

history, examination findings, first symptoms and age of onset were recorded. Where

available, neuropsychometry reports were reviewed, and additional investigations were

documented including electrophysiological assessments, MRI, CSF and tissue biopsies.

HTT CAG repeat length was recorded. Fisher’s exact test (Stata software) was used to

examine the relationship between the presence of particular clinical signs and gene test

outcome.

Hensman Moss 6

All C9orf72-positive cases were given a modified Goldman score21, 22, which was used to

quantify the strength of the autosomal dominant family history.

Standard Protocol Approvals, Registrations, and Patient Consents

Ethical approval to undertake these analyses was given by the local NHNN/ION ethics

committee. Informed consent for genetic studies was obtained from all participants.

Repeat primed PCR (rpPCR)

To test for the presence of an expansion at C9orf72, rpPCR was carried out as previously

described7. Fragment length analysis was undertaken on an ABI 3730xl automated

sequencer. Analysis of repeat primed PCR electropherograms was performed using Peak

Scanner v1.0 (ABI). Expansions with a characteristic ‘saw-tooth’ pattern were identified

and put forward for Southern blotting.

Rs3849942 genotyping

The surrogate marker rs3849942, reported to be associated with an increased risk of

mutation6, 14, was genotyped by allelic discrimination using the 5’ nuclease assay in

conjunction with Minor Groove Binding (MGB) probes. The assay was performed on the

SDS7500 Fast Real Time PCR system (ABI) and genotyping calls were made using

software v2.0.6.

Southern Hybridisation

A recently described Southern hybridisation protocol was used14. This combined the use of

an oligonucleotide (GGGGCC)5 probe which targets multiple sites within the expansion and

genomic DNA (gDNA) digested with two frequently cutting restriction endonucleases whose

Hensman Moss 7

sites closely flanked the repeat region. Hexanucleotide repeat number was estimated by

interpolation of autoradiographs using a plot of log10 base pair number against migration

distance which was created in Microsoft Excel.

Results

Genetic analyses

Of the 514 HD phenocopy cases screened, 10 probands (1.95%, 95% CI 1-4) were positive

for the C9orf72 expansion, making this mutation the commonest identified cause of HD

phenocopy syndromes in a UK cohort20.

Genotyping of the C9orf72-positive cases was consistent with all previous reports in that

these individuals were either heterozygous or homozygous for the rs3849942 A allele6

(Table 1). No C9orf72-positive cases had intermediate sized HD CAG repeats in the

Huntingtin gene, and there was no correlation between the larger HD normal allele and age

of onset.

Table 1.

Southern hybridisation (Table 1 and Figure 1) of 8/10 subjects for whom there was

sufficient DNA demonstrated that the size of expansion in this HD Phenocopy case series

was not significantly different from that found in series with other clinical presentations of

the C9orf72 expansion14. There was no significant difference in expansion size between

those with and without chorea/dystonia.

Hensman Moss 8

Figure 1: ‘Southern Blot of eight HD phenocopy patient DNAs’.

Of the entire cohort, 19.5% had a family history of similar neurodegenerative disease

whereas 70% of C9orf72-positive cases had a positive family history (see Goldman scores,

table 1). These results suggest that there is a predominance of those with family history,

but sporadic C9orf72-positive cases may be possible.

Clinical features of C9orf72 expansion gene carriers (table 2)

The mean age of onset was 42.7 years, range 8-60. Early psychiatric and behavioural

problems were common; they were the first recorded symptoms in six of the cohort.

Depression occurred in four, obsessions in two, apathy in two and psychosis in two cases.

Movement disorders were a prominent feature in this cohort - three exhibited chorea, four

dystonia, four myoclonus and three tremor. Six of the ten subjects had rigidity and five

bradykinesia. Chorea was observed periorally in one, was generalised with predominant

head and arm involvement in one, and in the left arm and leg in another. Of the four

subjects with dystonia, three were observed to have torticollis. In four of the ten subjects

upper motor neuron signs were noted; lower motor neuron signs were not observed in any.

Cognitively, executive dysfunction was noted in six subjects, and memory impairment was

present in six; in subject 6 for whom limited history was available, ‘cognitive impairment’

was noted.

Of eight cases with available MRI reports four had generalised atrophy.

Case 4 was found to be homozygous for the C9orf72 expansion mutation and has been

described in detail in Fratta et al23.

Hensman Moss 9

Comparisons between C9orf72 positive cases and the rest of the HD phenocopy

cohort

To examine whether there are particular HD phenocopy cases in whom C9orf72 testing

should be prioritized, we compared the frequencies of symptoms and signs between the

whole cohort and those with the expansion (table 3). Fisher’s exact test was performed to

investigate association between each clinical feature and the outcome of the C9orf72

genetic test. The presence of cognitive and psychiatric features, and some movement

disorder features (dystonia, bradykinesia/rigidity, tremor, myoclonus and upper motor

neuron features), were significantly associated with a positive C9orf72 test (table 3).

Though there may be some degree of ascertainment bias as more clinical detail was

recorded for positive cases, it remains clear that many symptoms characteristic of HD

phenocopies are associated with a C9orf72 gene expansion.

An illustrative case:

Case 5, a right-handed Caucasian woman, had a normal birth and development and was

university educated. She worked in a professional job and was well until a sudden

bereavement when she was fifty after which she became depressed.

At around 55y increasing fatigue was noted and she had her first falls, initially backwards.

She stopped working, and developed a change in personality with decreased interest in her

environment and child-like behaviour. She developed hypophonia and slurred speech.

By 58y she was having difficulty mobilizing and within 12 months went from independent-

living to being mute, profoundly bradykinetic and requiring a hoist to transfer. She

developed dystonic posturing of her feet and hands, and involuntary movements and a

tremor in her lower limbs.

Hensman Moss 10

In her family history, her father died of dementia without motor problems aged 69y.

She was admitted to hospital for investigation aged 60y. On examination there was akinetic

mutism with marked axial rigidity. There was left laterocollis, minor right torticollis, perioral

movements and occasional right cheek movements. There was broken pursuit and slow

broken saccades. There was moderate rigidity with spasticity in the upper limbs and severe

rigidity in the lower limbs. Plantars were extensor. Palmomental and pout reflexes were

present. There was perseveration and frontal features. MMSE (mini mental state

examination) was 16/25. (See supplementary information, case 1, for more detail of clinical

investigations undertaken.)

An unusual case:

Case 7, a right-handed Caucasian man, had a normal birth and early development. Aged

three at nursery school, it was noted that he did not mix well with the other children. At

primary school aged five he was found to have slight difficulties with writing; aged six he

was unable to follow basic lessons. Soon thereafter he was seen by an educational

psychologist and was diagnosed as having moderate learning difficulties and was

transferred to special needs school.

By age 8y, he had abnormal movements under stress, particularly affecting his hands and

head. These became a lot more prominent from 21y when they affected his walking.

Occasionally his right leg was noted to jerk uncontrollably from under him, and he had

some falls. The ‘fidgeting’ and jerking movements of hands and neck deteriorated. From

21y he had increased frustration and aggression.

His parents are non-consanguineous. His maternal grandmother died of motor neuron

disease; both parents were well.

Hensman Moss 11

Aged 23y he was admitted to hospital for investigation. Gait was slightly broad based, with

both arms tending to hold slightly dystonic postures, particularly on the right. There was

decreased arm swing, nuchal more than axial rigidity, unsteadiness on heel-toe walking,

and Romberg’s test was negative. Eye movements were abnormal, with poor gaze

initiation, impaired pursuit, saccadic hypometria with head thrusts, and reduced vertical up-

gaze. There was generalised chorea with mainly head and arm involvement, oro-buccal

chorea, myoclonic movements of the head and neck, and some additional dystonic

elements with mild bradykinesia. In the limbs there were prominent irregular myoclonic

jerks, exacerbated by movement and stimuli. Reflexes and sensation were normal.

MMSE was 20/28. On Neuropsychological examination, the Wechsler Adult Intelligence

Scale-Revised was within the defective range consistent with learning difficulties. There

was evidence of memory impairment for visual and verbal memory.

MRI scan showed one small lacune. Nerve conduction studies and electromyography were

normal. Electroencephalography revealed a diffuse and non-specific excess of theta activity

with only a trace of alpha like activity. Although the bursts of high voltage slow activity had

a bursting paroxysmal quality no definite epileptiform activity was seen. (See

supplementary information, case 2, for more detail of clinical investigations undertaken.)

Discussion

Huntington’s disease is the most common genetically determined neurodegenerative

disease with a prevalence of at least 12.4 per 100,000 people24, but in those in whom HD

is suspected but patients do not have a CAG repeat expansion in HTT, attaining genetic

diagnosis has been rare (2.8%20). Here we present data demonstrating that the C9orf72

Hensman Moss 12

expansion is the commonest-identified genetic cause of HD phenocopy presentations in a

UK cohort, with a prevalence of 1.95% (95% CI 1-4).

HD is an autosomal dominant condition, classically presenting with a triad of movement,

cognitive and psychiatric symptoms. However there is clinical heterogeneity, particularly

early in disease, and not all characteristic features may be apparent: 90% of adults with

HD develop chorea, but the clinical spectrum is broad, including Parkinsonian akinetic-rigid

syndromes and relatively pure dystonic, ataxic and psychiatric presentations25. Around 8%

of patients with HD present without an apparent family history of HD26. Because of this

clinical diversity, it is accepted3, 20 that any definition of Huntington’s disease phenocopy

syndromes need encompass not only the classical triad of HD but also syndromes having a

major degree of overlap with HD, and those without a known autosomal dominant family

history. Those patients with a clear family history of HD and with classical manifest HD are

more likely to have HD, however many patients seen by Neurologists do not present in

such a clear cut manner. Our cohort is composed of patients seen by experienced

neurologists in whom the diagnosis of HD was considered thus it reflects clinical reality. It

is UK-based, and given that UK-based cohorts have similar ethnic descent to other

European, Australian and North American cohorts, our findings are likely to be

representative of cohorts from these areas. In patients of African origin (particularly

Southern Africans), JPH3 expansion remains the commonest cause of HD-like

presentations27. Identifying the causes of HD phenocopy syndromes is of importance to the

diagnosis and management of patients with these presentations, as well as the counselling

of such individuals and their relatives in matters of genetic testing, life choices and

reproduction3.

Hensman Moss 13

Diagnostic tests for this novel mutation have recently become available. Many symptoms

characteristic of HD were associated with the subject being C9orf72 positive; given this,

and the high frequency of C9orf72 expansion among HD phenocopies mean that we

believe that it should be tested for in all HD phenocopy cases. In the future it is likely that

multi-gene ‘disease panels’ will supersede the need for sequential genetic testing, however

since C9orf72, like many other causes of HD phenocopies is an expansion mutation, it will

remain important for the clinician to be aware of which tests are most appropriate for

different patients and request them accordingly. We propose a revised clinico-genetic

algorithm for the investigation of HD phenocopy cases in Figure 2.

Figure 2: ‘Algorithm for the investigation of HD phenocopy cases’.

The effects of the C9orf72 expansion are known to be both clinically and pathologically

varied28 and it is the major cause of both familial and sporadic ALS and FTLD, which are

themselves phenotypically heterogeneous conditions. Parkinsonism, particularly rigidity

and bradykinesia, has been previously noted in C9orf72-positive individuals29-31; the

C9orf72 mutation has been found in some cohorts of patients with Parkinson’s disease32

and not others30, 33, 34. In this study we have demonstrated that the clinical phenotypes

caused by C9orf72 expansion mutations are broader than previously noted to date. It can

present with a movement disorder including chorea, dystonia, myoclonus and tremor. The

combination of movement disorder, cognitive decline and psychiatric and behavioural

problems, often with a family history of similar problems, explains why C9orf72-positive

cases can have a presentation very similar to HD. It is notable that ALS-type symptoms

were relatively infrequent in the HD phenocopy C9orf72 cases: none had lower motor

neuron signs, while 40% had upper motor neuron signs. By contrast, symptoms more

Hensman Moss 14

characteristic of FTLD such as cognitive impairment were much more prevalent, suggesting

that there is more overlap between the HD-like and FTLD-like cases.

The average age of onset for C9orf72 in published reports is around 57 years7, 9, 31, 35, in

this study it is lower at 42.7 years, with range 8 – 60, suggesting that the condition should

be considered in the differential diagnosis not only in a wider range of clinical presentations,

but in a wider demographic group than previously identified.

We examined whether the difference in phenotype could be accounted for by a different

size of expansion by Southern hybridisation: the size of expansion in our HD phenocopy

cohort was not significantly different from that of other cohorts14. Furthermore, among the 8

C9orf72-positive subjects examined here, there is no statistically significant association

between expansion size and age of onset. Case 7, who had motor onset at 8y, underwent

whole-exome sequencing; no large-scale structural abnormalities were detected. An

important caveat is that there is evidence of reduced penetrance of the C9orf72 expansion

given that the population frequency of C9orf72 expansion is 1 in 69114 in the UK population,

so there is a small possibility of false positives accounting for one or more of these unusual

presentations of C9orf72 mutations.

Among the ten HD phenocopy C9orf72 cases, there was a tendency for those with chorea

and dystonia to have younger ages of onset than those without them: the average age of

onset of subjects with chorea/ dystonia in this cohort is 28.3, whereas the average age of

onset of those without them is 54.8 (P=0.019, Independent samples Mann-Whitney U-test).

This may reflect our ascertainment criteria, since HD-phenocopy cases are more likely to

Hensman Moss 15

be young and have movement disorders than FTLD or ALS cases. However, it is possible

that the C9orf72 expansion with these motor symptoms manifests with earlier onset.

Incomplete penetrance has been previously suggested in C9orf72 expanded individuals36,

13, 31 which has important implications for genetic testing. In this case series there was no

reported family history in three cases, and case 7’s family history is compatible with

incomplete penetrance – the subject’s maternal grandmother had MND, but the mother was

well.

We have presented a large case series which not only demonstrates that the C9orf72

expansion is the most frequent cause of HD phenocopy presentations in this UK-based

population, but also that the phenotype of the C9orf72 encompasses a diversity of

movement disorders, and a younger age of onset than previously recorded.

Acknowledgements

We are grateful the patients who participated in this study. We also acknowledge Ailbhe

Burke for work on the NHNN HD phenocopy cohort database, Mark Gaskin for help with the

curation and plating of samples and James Uphill for technical advice.

Hensman Moss 16

Figure Legends

Figure 1: ‘Southern Blot of eight HD phenocopy patient DNAs’. Southern Blot of eight HD phenocopy patient DNAs, showing that C9orf72 repeat expansions can be seen in all cases. The asterisk indicates a GGGGCC containing a short-tandem-repeat genome motif unrelated to C9orf72. The samples are ordered from 1 – 8 from left to right; there was insufficient DNA to blot samples 9 and 10. The blot for cases 1 – 6 has been previously published14. (Reprinted with permission from Elsevier.)

Figure 2: ‘Algorithm for the investigation of HD phenocopy cases’. Proposed clinico-genetic algorithm for the work-up of Huntington’s disease phenocopy patients, highlighting key diagnoses to be considered. SCA, Spinocerebellar ataxia; HDL2, Huntington’s disease-like 2, DRPLA, dentatorubral-pallidoluysian atrophy; NBIA, Neurodegeneration with Brain Iron Accumulation.

Hensman Moss 17

Subject Age

at

onset

Rs3849942

genotype

Expansion size

estimated by

southern

hybridisation

Goldman

score

1 60 AA 4010 4.5

2 56 GA 3441 1

3 55 AA 3682 1

4 36 AA 3180 1

5 50 GA 2939 3

6 56 GA 2939 0

7 8 GA 3186 3

8 44 GA 3518 3

9 19 AA insufficient DNA 4.5

10 58 GA insufficient DNA 3

Table 1: Age at onset and genetic results of C9orf72

expansion positive cases

Hensman Moss 18

Clinical

feature

1 2 3 4 5 6 7 8 9 10

Chorea √ √ √

Myoclonus √ √ √ √

Dystonia √ √ √ √

Tremor √ √ √

Rigidity √ √ √ √ √ √

Bradykinesia √ √ √ √ √

Torticollis √ √ √

UMN signs √ √ √ √

Depression √ √ √ √

Anxiety √ √

Apathy √ √

Executive

dysfunction

√ √ √ √ √ √

Impaired

memory

√ √ √ √ √ √

Impaired

face

recognition

√ √ √

Impaired

verbal

√ √ √

Hensman Moss 19

fluency

Table 2: Summary of the clinical features of ten C9orf72 expansion-positive cases.

UMN = upper motor neuron.

Hensman Moss 20

Number in

C9orf72 negative

cases (N=504)

(Percentage)

Number in C9orf72

positive cases

(N=10)

(Percentage)

Number in

whole HD

phenocopy

cohort (N=514)

(Percentage)

P value

(Fisher's exact

test)

All

movement

disorder

features

394 (78%) 8 (80%) 402 (78%) 1

Chorea 154 (31%) 3 (30%) 157 (31%) 1

Dystonia 53 (11%) 4 (40%) 57 (11.1%) 0.017

Bradykinesi

a/ rigidity

78 (15%) 6 (60%) 84 (16%) 0.002

Tremor 39 (8%) 3 (30%) 42 (8%) 0.041

Ataxia 72 (14%) 1 (10%) 73 (14%) 1

Myoclonus 31 (6%) 4 (40%) 35 (7%) 0.003

UMN

features

18 (4%) 4 (40%) 24 (5%) <0.001

LMN

features

8 (1.6%) 0 (0%) 8 (2%) 1

Psychiatric

problems

53 (11%) 7 (70%) 60 (12%) <0.001

Depression 17 (3%) 4 (40%) 21 (4%) 0.035

Hensman Moss 21

Anxiety 4 (0.8%) 2 (20%) 6 (1%) 0.005

Cognitive

impairment

167 (33%) 9 (90%) 176 (34%) <0.001

Executive

dysfunction

19 (4%) 6 (60%) 25 (5%) <0.001

Memory

problems

29 (6%) 9 (90%) 176 (34%) <0.001

Family

history

98 (19%) 7 (70%) 105 (20%) 0.001

Table 3: Phenotypic features of C9orf72 negative & positive cases within HD

phenocopy cohort, and outcome of Fisher's exact test to test for association

between clinical feature and genetic test outcome.

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References:

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